ETC2 is a single player mod made by DaveJ for Half Life. Set within the Half Life universe, it brings back Gordon Freeman to fight against aliens, zombies and soldiers.
Since an ETC's ModDB website doesn't exist, I guess I have to rate both ETC and ETC 2 here.
Both of them offer classic Half-Life action without much of a story (having no storyline is not a bad thing!). The gameplay is well balanced and the level design is very good. I recommend playing this mod.
I prefer to rate both of them as if they were a single mod. So generally, they deserve 9/10. In my opinion ETC 2 was a little better than the first one.